How to build static lib .a on QTcreator windows 7

[nhs_0702]

I want to create a static library .a by QTcreator with a platform on a windows 7,

I want to write function is simply this:

int sumint(int a,int b)
{
     return a+b;
}

int sumint(int a,int b)
{
     return a+b;
}

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can you help me ?